package com.tc.groovy

import java.lang.reflect.Method

/**
 * Created by cai.tian on 2018/1/18.
 */
public class BeanUtil {

    public static final BeanUtil INSTANCE=new BeanUtil();

    public static final String PREFIX_GETTER_IS="is";
    public static final String PREFIX_GETTER_GET="get";
    public static final String PREFIX_SETTER="set";
    public static final String PREFIX_ADDER="add";

    /**
     *
     * @param method to check if it is an 'adder' method.
     * @return true if the given method is an 'adder' method.
     */
    public boolean isAdder(Method method) {
        int parameterCount = getParameterCount(method);
        if(parameterCount!=1){
            return false;
        }
        Class<?> returnType = method.getReturnType();
        if(returnType!=void.class){
            return false;
        }
        String methodName = method.getName();
        return methodName.startsWith(PREFIX_ADDER);
    }

    /**
     *
     * @param method to check if it is a standard java beans getter.
     * @return true if the given method is a standard java beans getter.
     */
    public boolean isGetter(Method method) {
        int parameterCount = getParameterCount(method);
        if(parameterCount>0){
            return false;
        }
        Class<?> returnType = method.getReturnType();
        if(returnType==void.class){
            return false;
        }
        String methodName = method.getName();
        if(!methodName.startsWith(PREFIX_GETTER_GET)&&!methodName.startsWith(PREFIX_GETTER_IS)){
            return false;
        }
        if(methodName.startsWith(PREFIX_GETTER_IS)){
            if(!returnType.equals(boolean.class)&&!returnType.equals(Boolean.class)){
                return false;
            }
        }
        return true;
    }

    private int getParameterCount(Method method) {
        return method.getParameterTypes().length;
    }

    /**
     *
     * @param method to check if it is a standard java beans setter.
     * @return true if the given method is a standard java beans setter.
     */
    public boolean isSetter(Method method){
        int parameterCount = getParameterCount(method);
        if(parameterCount!=1){
            return false;
        }
        Class<?> returnType = method.getReturnType();
        if(returnType!=void.class){
            return false;
        }
        String methodName = method.getName();
        if(!methodName.startsWith(PREFIX_SETTER)){
            return false;
        }
        return true;
    }

    /**
     * @param method to get the associated property name for.
     * @return The property name of the associated property if the given method matches a standard java beans getter or setter.
     */
    public String getPropertyName(Method method) {
        String methodName = method.getName();
        String rawPropertyName=getSubstringIfPrefixMatches(methodName,PREFIX_GETTER_GET);
        if(rawPropertyName==null){
            rawPropertyName=getSubstringIfPrefixMatches(methodName, PREFIX_SETTER);
        }
        if(rawPropertyName==null){
            rawPropertyName=getSubstringIfPrefixMatches(methodName,PREFIX_GETTER_IS);
        }
        if(rawPropertyName==null){
            rawPropertyName=getSubstringIfPrefixMatches(methodName,PREFIX_ADDER);
        }
        return toLowerCamelCase(rawPropertyName);
    }

    /**
     * Converts the given String into lower camel case form.
     * @param string to decapitalize.
     * @return null if the given String is null.
     * Emtpy string if the given string is empty.
     * The given string if the first two consecutive letters are in upper case.
     * The given string with the first letter in lower case otherwise, which might be the given string.
     */
    public String toLowerCamelCase(String string){
        if(string==null){
            return null;
        }
        if(string.isEmpty()){
            return string;
        }
        if (string.length() > 1 && Character.isUpperCase(string.charAt(1)) &&
                Character.isUpperCase(string.charAt(0))){
            return string;
        }
        char[] chars = string.toCharArray();
        chars[0] = Character.toLowerCase(chars[0]);
        return new String(chars);
    }

    private String getSubstringIfPrefixMatches(String wholeString,String prefix) {
        if(wholeString.startsWith(prefix)){
            return wholeString.substring(prefix.length());
        }
        return null;
    }

}
